1. Field of the Invention
The present invention relates generally to a longitudinal perforation forming apparatus for a form printing machine. More particularly, the invention relates to an arbitrarily positioned longitudinal perforation forming apparatus for forming a longitudinal perforation at an arbitrary position or a selected position in a continuous web paper printed by a form printing machine, depending upon a printed image.
2. Description of the Related Art
Since a form printing machine prints by means of a plate cylinder having a predetermined peripheral length, printing on a continuous web paper repeatedly makes a print per predetermined length in a feeding direction of the continuous web paper. In other words, printing using the plate cylinder makes repeated prints of the same image. Then, when a lateral or cross line perforation aligned in a perpendicular direction to a longitudinal direction of the continuous web paper is formed in a part of the printed image of such repeated prints of the same image, it is typical to perform a formation of the perforation by means of a perforation forming cylinder or a roulette cylinder having the same peripheral length as the plate cylinder in a similar manner to printing. In such conventional apparatus, the perforation formation is inherently performed sequentially and repeatedly for all printed images. Therefore, it has not been possible to form a longitudinal perforation only for a preliminarily selected image.
For example, in a longitudinal perforation forming apparatus composed of a roulette cylinder and a receptacle cylinder, a prior art apparatus which forms a longitudinal perforation for a part of the printed image is illustrated in FIGS. 11 and 12.
The apparatus shown in FIGS. 11 and 12 is called a skip roulette apparatus. The skip roulette apparatus has the receptacle cylinder a on the peripheral surface of which ribbon steels b are attached at mutually spaced apart positions with a predetermined distance in axial direction. At positions corresponding to respective ribbon steels b, longitudinal roulette rollers c are provided and are supported by holders d. Rotating the holders d according to rotation of the receptacle cylinder a to depress the longitudinal perforation rollers c onto the ribbon steels b forms a longitudinal perforation in the web paper e.
In the foregoing conventional skip roulette apparatus, the longitudinal perforation is formed in a part of the printed image by attaching the ribbon steel corresponding to the length of the longitudinal perforation on the receptacle cylinder a having the same peripheral length of a plate cylinder. However, it has not been possible to selectively form the longitudinal perforation. Also, since the position of the longitudinal perforation is fixedly determined depending upon the position where the ribbon steel is attached, varying the position or interval is difficult. Furthermore, in order to vary the position of the longitudinal perforation in the longitudinal direction (traveling direction of the continuous web paper), it becomes necessary to loosen a sleeve f supporting the receptacle cylinder a to manually adjust the longitudinal position. Such adjustment is not easy. Furthermore, it is difficult to change the number of longitudinal perforations, similarly.